There are certain situations where the closure of an opening is important for reasons of safety, i.e., to prevent the spread of a hazardous condition (such as fire or flooding) from one area to another. During these emergency situations it has been recognized that a door should be able to close off an opening without the need of a power system because it, or the emergency detection device that initiates the power system, may become non-functional during the emergency itself. It is also desirable to eliminate the need for manned intervention because the hazardous condition may not give workers or occupants enough time to react to the situation.
This is especially true of offshore vessels such as oil drilling or production platforms. Offshore oil platforms are susceptible to storms, flooding, fire, etc. and are especially vulnerable because of their inaccessibility and potential for great loss due to the sinking of the entire vessel. To illustrate this point, there have been two recent sinkings of floating offshore drilling platforms, the Alexander Keeland, in 1980, and the Ocean Ranger, in 1982. In both cases, unclosed openings contributed to uncontrolled flooding of these vessels. Generally, what happens is that some event such as an impact or storm causes heeling (listing of the vessel) and localized flooding which, due to the network of intercommunicating passages, accelerates both the heeling and flooding. The result of this additive relationship is that the vessel rapidly sinks.
To ensure that passageways will be closed during these emergency situations, it is necessary to invent a device that is free from the limitations of both the power assisted or manual intervention methods. The present invention remedies this problem by using gravity to move the closure over the opening. By doing this, the deficiencies inherent in power assist and manual intervention are eliminated. Patented examples of gravity assisted closure devices are U.S. Pat. Nos. 4,357,732 and 3,832,754. U.S. Pat. No. 4,357,732 discloses an automatic door closure kit that may be mounted on an existing sliding glass door. U.S. Pat. No. 3,832,754 shows self actuating door hinges that operate by gravity.
Consequently, it is an object of this invention to create a door closure that will operate without the need for manned intervention or a power source. It is another object of this invention to develop a door closure device that is actuated by gravity. It is another object of this invention to develop a door closure device that will restrict hazardous conditions such as fire and flooding to a localized compartment.